This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 100 23 445.3, filed on May 12, 2000, the entire disclosure of which is incorporated herein by reference.
The invention relates to a terry loom with a first thread supply arrangement for supplying a ground warp thread sheet and a second thread supply arrangement for supplying at least one pile warp thread sheet, shed forming elements for shedding the-warp sheets, and cloth drawing-in means.
Various methods and equipment are known for weaving a terry cloth with loops of a pile thread bound in by the weft threads. Typically, the pile loops are formed by a pile warp, while a further ground warp cooperates with the weft threads to form the base cloth. In this regard, the terry loom includes the components mentioned above and further includes weft insertion means and a reed or other weft beat-up means that cooperate with the above mentioned shed forming elements in a conventional manner.
More particularly, to form the terry cloth, the respective weft threads are first inserted and partially beat-up along a line at a prescribed spacing distance from the beat-up edge or cloth fell. Then, in a subsequent step the weft threads are fully beat-up against the beat-up edge of the cloth in a group-wise manner by performing a so-called full beat-up or group beat-up. While carrying out this group beat-up with the reed, the tension of the pile warp threads is reduced and additional lengths of the pile warp threads are supplied, so that the relatively loose pile warp threads are pushed along with the weft threads during the beat-up. Thereby the pile warp threads form pile loops puckering outwardly away from the base warp or ground warp. At the same time, the weft threads glide along between the round warp threads, which are held under tension, until the weft threads reach their final beat-up position against the beat-up edge of the cloth.
These are merely the most basic aspects of the generally known technique of terry weaving, which is described in further detail, for example in the book xe2x80x9cWEBEREI Verfahren und Maschinen fuer die Gewebeherstellungxe2x80x9d (Weaving Methods and Machines for Woven Cloth Productionxe2x80x9d) by Dipl.-Ing. J. Schneider, published by Springer-Verlag Berlin/Gxc3x6ttingen/Heidelberg, 1961, pages 17 and 277.
A typical example of a terry weaving loom is known from German Patent 2,225,604, which also illustrates and describes the basic construction of such a terry weaving loom. The ground warp threads are fed or let out from a ground warp thread beam and are deflected over a spring-loaded tensioning beam into the horizontal weaving plane, in which they are combined and united with the pile warp thread sheet which is fed or let out from a pile warp thread beam located above the weaving plane. Thus, the pile warp thread sheet and the ground warp thread sheet are united to form a common warp thread sheet including the interspersed ground warp threads and pile warp threads. The pile warp threads are guided over their own separate spring-loaded tensioning beam which is arranged above the ground warp thread sheet and extends across the weaving width so as to direct and introduce the pile warp threads from above, essentially tangentially into the ground warp thread sheet.
Further according to DE 2,225,604, the ground warp threads and the pile warp threads run through warp thread stop motions arranged in the weaving plane. Then, behind or downstream of these stop motions, the ground warp threads and pile warp threads in common run through shed forming elements in the form of healds or heddles, and from there extend through the weaving reed to the woven web edge which forms the so-called beat-up edge. The loom shed that is formed by the heddles according to the selected weaving pattern has the shed vertex of the front shed defined along the beat-up edge, and ends with the shed vertex of the back shed in the area of contact rods of the warp thread stop motion that serves in common for monitoring the ground warp threads and the pile warp threads.
The weft threads are respectively inserted into the open shed by the weft insertion means. Then, the weaving reed, for example cooperating with or carried by a sley that is not shown in detail, carries out a back-and-forth weft thread beat-up motion having a constant amplitude. Thereby, the successive weft threads inserted into the loom shed are first partially beat up into a partial beat-up position at a spacing distance away from the beat-up edge of the woven cloth, and then respective successive groups of the partially beat-up weft threads are group-wise completely beat-up against the beat-up edge of the woven cloth. To achieve this, the breast beam is controlled by a so-called terry eccentric so that the breast beam moves toward the reed, whereby the woven cloth also moves toward the reed, so that the constant amplitude beating of the reed can carry out the complete or group beat-up of the weft threads against the beat-up edge of the woven cloth. During this motion of the breast beam, the warp thread sheet is held under tension by the spring-loaded tensioning beam. Since the entire woven cloth and warp thread sheet are moved cyclically in this known method, one speaks of a xe2x80x9cwoven web motion controlxe2x80x9d for the loop formation of the pile threads.
In the above described known method and equipment, problems can arise while guiding together and combining the pile warp thread sheet with the ground warp thread sheet, particularly because neighboring pile warp threads can become hung-up or caught on one another while being let off from the pile warp beam, or the neighboring pile warp threads may even become partially looped around one another and thus tangled. These problems are especially more likely to occur because the pile warp thread tension must be reduced during the group beat-up in order to form the pile loops in the pile-warp threads. There are certain types of thread or yarn that have a particularly strong tendency toward such tangling, due to their characteristics, their thread structure, or the fiber material contained therein. If such pile warp threads that are hung-up or tangled with one another are fed into a warp thread stop motion in common with the ground warp threads, or especially all the way to the back shed and to the heddles, there is a danger that warp thread breaks or at least weave defects will arise.
The removal or correction of warp thread breaks inn the area of the back shed in such looms is particularly difficult because the warp thread stop motions and the warp thread area between the stop motions and the tensioning roller for the pile warp threads is very difficult to accesss from the warp beam side. This is the case, because these areas are substantially covered by the pile warp thread sheet in the manner of a curtain that extends practically entirely down to the weaving plane. Thus, in order to remove or correct warp thread break, the operating personnel must reach through and between the pile warp threads and then search for the broken warp thread ends that are to be connected to each other, using a wire hook or some other suitable tool.
Since the warp thread stop motions are arranged in an area of the back shed in which the pile warp thread sheet runs into the ground warp thread sheet at a rather small acute angle relative to the weaving plane, this leads to the additional problem that a relatively strong back and forth motion of the pile warp threads arises in the area of the warp thread stop motion during the shed forming and pile loop forming operations. Such strong motion of the pile warp threads is undesirable, for example due to rubbing wear of the threads and resultant formation of fly lint, especially when weaving with rather sensitive pile warp threads. Moreover, due to this arrangement of the warp thread stop motion directly in front of the area of the back shed, the warp thread movements also have a strong influence on the pile warp thread stop motion feelers during the group beat-up, with the result that forces arise in the pile warp threads which act contrary to the pile loop forming process. In other words, the arising tension forces tend to hinder the proper formation of the pile loops in the pile warp threads during the group beat-up.
As described above, in the known terry loom according to German Patent 2,225,604, only the breast beam is moved for achieving the required woven cloth motion control during the group beat-up, while the warp thread tension of the ground warp thread sheet is maintained by the corresponding allocated spring-loaded tensioning beam. On the other hand, European Patent Publication EP 0,768,407 Al discloses a terry loom in which the required woven cloth motion control is achieved by the backrest beam or roller of the ground warp thread sheet being positively coupled through a linkage with the cloth drawing-in roller, so that these two components together carry out the relative motion with respect to the beat-up location of the reed, as required for the formation of the pile loops. By appropriately adjusting and controlling this coupling between the backrest beam and the cloth drawing-in roller, the pile height can be varied according to a selected pattern, as is known from the European Patent Publication EP 0,979,891 A1. Also in these known terry looms, the pile warp thread sheet runs over a spring-loaded compensating roller arranged above the weaving plane and the ground warp thread sheet, and from there runs at a small acute angle from above into the ground warp thread sheet. Thereby, the pile warp threads first interpenetrate between the ground warp threads in the area of the back shed. The warp thread stop motions can therefore only be arranged in the same manner as described above.
In order to provide the additional pile warp thread length that is needed for the proper loop formation during the group beat-up, German Patent Publication DE 196 26 417 A1 discloses a terry loom having a deflecting rod for the pile warp threads, whereby this deflecting rod is coupled with a pile warp thread tensioning device in the form of a tensioning roller. Particularly, the deflecting rod is arranged before or upstream of this pile warp thread tensioning device in the thread running direction, in such a manner so as to form a deflection location for the pile warp threads that essentially faces toward the rotation axis or pivot axis of the tensioning device. Thereby, the tension arising in the pile warp threads during the loop formation is compensated. However, also in this known terry loom, the pile warp threads run from above at a small acute angle relative to the weaving plane, coming directly from the pile warp thread tensioning device and from there being guided almost parallel to the weaving plane, so that the pile warp threads only run into the ground warp threads in the back shed. The arrangement of the warp stop motions is not shown in further detail in the reference.
In a different terry loom known from the European Patent Publication EP 0,257,857, the pile warp thread beam is arranged at the bottom, while the ground warp thread beam is supported at a spacing distance above the weaving plane. With this reversed arrangement of the warp beams, however, nothing else is changed with regard to the basic aspects and relationships described above in connection with other known terry looms. Namely, the pile warp threads finally run into, i.e. become interspersed with, the ground warp threads only in the area of the back shed, whereby the warp stop motions for both warp thread systems are arranged in or on the back shed, and both the pile warp threads and the ground warp sheds run in common through the warp stop motions.
While the above described known looms use the so-called woven cloth motion control (i.e. controlled movement of the woven cloth) for carrying out the loop formation and the complete group beat-up, there are also other terry weaving looms in which the loop or pile formation is carried out with a so-called sley control, for example as described in the European Patent Publication 0,298,454 B1 and in the above mentioned technical reference book xe2x80x9cWEBEREIxe2x80x9d at page 277. In any event, even in such other terry weaving looms, the above described relationships and guidance of the ground warp threads and the pile warp threads are essentially carried out in the same manner as described above. In general it can be said that terry weaving is more difficult and more complex in comparison to flat weaving. Thus, in the known terry weaving looms, it is always exclusively the most important function to ensure that the loop formation, the warp tension regulation for the ground warp threads and the pile warp threads, as well as the warp thread monitoring by stop motions can be carried out without defects or problems for the practical production of woven terry cloths. On the other hand, generally little attention is paid to the accessibility, maintainability and ease of operation with respect to the warp stop motions and the like, in these often quite complicated machines. In view of the ever increasing capacity of commercial weaving looms, there is a constant trend toward using ever more warp beams with greater volume capacities, whereby the accessibility of the warp stop motions for operating or maintaining the same is further degraded or hindered.
In view of the above it is an object of the invention to provide a terry weaving loom which can achieve a high output capacity and operational reliability, while simultaneously achieving an improved ease of operation and maintenance. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a loom arrangement in which the ground warp thread sheet and pile warp thread sheet are respectively individually guided through separate warp thread stop motions, which are arranged to be freely accessible from at least one side of the machine, i.e. from the warp beam side or from the woven cloth side. Preferably, the warp stop motion for the ground warp thread sheet and the warp stop motion for the pile warp thread sheet are arranged on two different planes that are spaced vertically aid horizontally from one another, whereby generally the accessibility is further improved. Particularly, at least the pile warp thread sheet is guided in a preferably horizontal plane in the area of the pile warp thread stop motion. Especially due to the arrangement of the pile and ground warp thread stop motions in two different planes, the removal or correction of warp thread breaks becomes especially user-friendly.
Furthermore, the pile warp threads are guided to penetrate through the ground warp thread sheet so as to form a thread cross of the pile warp threads and the ground warp threads. Due to such a thread cross arrangement, any warp thread break in the area of the back shed can be easily observed and recognized and then simply removed or corrected by the operating personnel. In a particularly advantageous embodiment of the invention, the pile warp thread sheet is guided through the ground warp thread sheet so as to interpenetrate and intersect the ground warp thread sheet in a cross configuration, particularly at a steep angle, for example between 45 and 135xc2x0, or particularly between 75 and 135xc2x0, or more particularly 70 to 130xc2x0, or even 80 to 100xc2x0, as measured between the pile warp thread sheet and the ground warp thread sheet on the upstream or supply side thereof relative to the thread intersection or crossing point. This intersection or crossing point is located in an area between the back shed of the pile warp threads formed by the shed forming elements such as heddles, and the warp thread supply arrangement supplying the ground warp thread sheet.
Since-the pile warp thread sheet is guided through, i.e. intersecting, the ground warp thread sheet outside of and upstream from the back shed, there is formed a thread cross of the pile warp threads, and the ground warp threads, which ensures a reliable separation of the individual pile warp threads or pile warp thread groups from each other, because they are respectively interspersed between successive ground warp threads. Depending on the binding pattern, either properly separated individual pile warp threads, or groups of pile warp threads (generally at most two threads) corresponding to the pattern repeat, are guided respectively to the individual heddles, whereby the threads in such groups can be arranged lying side-by-side next to one another or one over another. Due to the thread cross formed in this manner, any arising warp thread break in the area of the back shed may be easily observed and recognized, and then removed or corrected without difficulties from the warp beam side or from the woven cloth drawing-off side.
The inventive terry weaving loom advantageously includes deflecting means, i.e. a deflecting element such as a deflecting rod, for deflecting the pile warp threads. The deflecting element or deflecting means may comprise at least one deflecting rod over which the pile warp thread sheet is deflected and guided. The deflecting rod can be embodied as a jointed rod which is respectively braced and supported at several locations across the weaving width. In order to keep the frictional forces low, the deflection rod can be rotatably supported, and it can also be advantageous to support the deflection rod in a spring-loaded yieldable or movable manner, and also mechanically adjustably.
The deflecting element is preferably arranged on the side of the ground warp thread sheet opposite the warp thread supply arrangement which supplies the pile warp thread sheet. With this arrangement, the pile warp thread sheet is caused to penetrate through the ground warp thread sheet in a cross formation as described above. Depending on the spatial characteristics and the particular construction of the loom at hand, the inventive arrangement can be carried out in such a manner that the pile warp thread sheet and the ground warp thread sheet form an acute angle or an obtuse angle with respect to each other at the thread crossing location, as seen in the thread running direction. Particularly, the two warp threads sheets can cross each other at an angle of approximately 90xc2x0, e.g. in the range from 80 to 100xc2x0.
The deflection point provided by the deflecting rod is thus directly adjacent to the thread cross mentioned above. This deflection location of the pile warp threads serves to avoid a strong back-and-forth movement of the pile warp threads in the area of the pile warp thread stop motion. Additionally, the pile warp thread sheet is preferably guided over an arrangement for forming a pile warp thread reserve in an area lying before or upstream of the thread crossing location at which the pile warp thread sheet intersects and penetrates through the ground warp thread sheet, as seen in the-thread running direction. This arrangement for forming a pile warp thread reserve serves to compensate the length of the pile warp threads during the pile loop formation and/or during the shed changing. This arrangement for forming a pile warp thread reserve can comprise at least one spring-loaded yieldingly supported thread length compensating element, which the pile warp threads at least partially loop around or over. For example, this element may be a spring-elastically supported deflecting rod or a spring-yielding or yieldingly supported thread deflecting metal sheet or plate.
The above described guidance of the warp threads makes it possible to store the required or the arising pile warp thread length for the thread formation during terry weaving with woven cloth motion control or with sley motion control (as respectively described above) in such a manner so that the pile warp thread tension is reduced before the group beat-up, and the spring-loaded deflecting rod or the spring sheet metal deflecting plate or sheet at least partially takes up the pile warp thread length. Thereby it is achieved that the group beat-up does not have such a strong effect on the pile warp stop motion feelers as was the case in the prior art, so that thread tension forces that would be contrary to the pile loop forming process are minimized.